2001A&A...379..229Y


C.D.S. - SIMBAD4 rel 1.7 - 2021.04.12CEST23:32:28

2001A&A...379..229Y - Astronomy and Astrophysics, volume 379, 229-234 (2001/11-3)

Speckle interferometry and radiative transfer modelling of the Wolf-Rayet star WR 118.

YUDIN B., BALEGA Y., BLOECKER T., HOFMANN K.-H., SCHERTL D. and WEIGELT G.

Abstract (from CDS):

object{WR 118} is a highly evolved Wolf-Rayet star of the WC10 subtype surrounded by a permanent dust shell absorbing and re-emitting in the infrared a considerable fraction of the stellar luminosity. We present the first diffraction-limited 2.13µm speckle interferometric observations of WR 118 with 73mas resolution. The speckle interferograms were obtained with the 6m telescope at the Special Astrophysical Observatory. The two-dimensional visibility function of the object does not show any significant deviation from circular symmetry. The visibility curve declines towards the diffraction cut-off frequency to ∼0.66 and can be approximated by a linear function. Radiative transfer calculations have been carried out to model the spectral energy distribution, given in the range of 0.5-25µm, and our 2.13µm visibility function, assuming spherical symmetry of the dust shell. Both can be fitted with a model containing double-sized grains (``small'' and ``large'') with the radii of a=0.05µm and 0.38µm, and a mass fraction of the large grains greater than 65%. Alternatively, a good match can be obtained with the grain size distribution function n(a)∼a–3, with a ranging between 0.005µm and 0.6µm. At the inner boundary of the modelled dust shell (angular diameter Θin=(17±1)mas), the temperature of the smallest grains and the dust shell density are 1750K±100K and (1±0.2)x10–19g/cm3, respectively. The dust formation rate is found to be (1.3 ±0.5)x10–7M/yr, assuming Vwind=1200km/s.

Abstract Copyright:

Journal keyword(s): techniques: image processing - circumstellar matter - stars: individual: WR 118 - stars: mass-loss - stars: Wolf-Rayet - infrared: stars

Simbad objects: 6

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Number of rows : 6

N Identifier Otype ICRS (J2000)
RA
ICRS (J2000)
DEC
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2021
#notes
1 HD 162757 PM* 17 53 03.5399295183 -10 53 58.435171605   7.300 6.176     K1V 20 0
2 HD 164270 WR* 18 01 43.1452971756 -32 42 55.161881733 8.52 8.97 8.74 9.51   WC9d+? 217 0
3 MR 80 WR* 18 02 04.1238716757 -23 37 42.144766363   14.85       WC9 213 2
4 HD 168206 WR* 18 19 07.3628284656 -11 37 59.165038875 9.65 9.88 9.10     WC8+O8/9III/V 288 1
5 RAFGL 2179 WR* 18 31 42.2117071870 -09 59 16.687501795   25.0 22.0     WC9 86 0
6 EM* AS 320 WR* 18 44 13.1527220304 -03 47 57.779718279 13.7 13.340 13.983     WC9d 114 0

    Equat.    Gal    SGal    Ecl

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2021.04.12-23:32:28

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